After much debate in Washington, DC, and with the civil war brewing, Judah presented a transcontinental railroad a “Think Big” project. Asa Whitney had lobbied for a western railroad starting in 1847 but got nowhere. Somehow, Judah cut through the other issues (especially slavery) to get attention and became a central plank of the Republican platform.
The hardest engineering challenge was finding a suitable path over the Sierra mountains. Teaming with Daniel Strong, who wanted a road to his small town, Judah found a pass that worked.
Judah then needed to raise money for the last part of the railroad. He sold small shares to many people, but his Central Pacific Railroad lead funders included the “Big Four”: Leland Stanford (railroad President), Collins Huntington (VP), Mark Hopkins (Treasurer); Charles “Bull” Crocker called himself a construction supervisor though expressed a desire only to make money. It was Crocker who, during construction, famous hired Chinese laborers. Prominent jeweler and smaller investor James Bailey became Secretary.
Judah was the Chief Engineer; he also played a key role by leading key Congressional committees on railroad funding.
On July 1, 1862, Lincoln signed the law (written by Judah) providing loan guarantees for the railroad.
The Big Four, and later allies, exercised an option to force Judah to convert his shares to bonds. He retained a repurchase option but, on his way back east to find funding, died of yellow fever.
On May 10, 1869, the railroad was finished. Each of the Big Four made a fortune. Leland Stanford eventually donated much of his wealth, and his large ranch in Palo Alto, for the creation of Stanford University. Crocker famously donated none of his fortune before or after his death.
Besides the Central Pacific Railroad, the Congressional authorization, arranged by Judah, also financed a complementary line, built by Union Pacific, that connected to Central Pacific line.
Since railroad builders were paid, by the government, for each mile of track they laid both the Central Pacific and Union Pacific famously competed to build faster until the lines met.